Digimon: Digital Monsters (1999 - Current)

To many, it looks like a Pokemon clone, but Digimon holds it's own with it's own original style.

Seven kids (Taichi kamiya 11, Sora Takenouchi 11, Yamato Ishida 11, Kohshiroh Izumi 10, Mimi Tachikawa 10, Takeru Takaishi 8, & Joe Kido 12) get called into an alternate dimension called the Digital World, where objects exist as computer data, and befriend a group of digital monsters(known as Digimon) to help defend the world from an uprising force of evil. Through training, each monster can gradually grow into more powerful monsters, from rookie, champion, ultimate, and finally to mega. In their more powerful forms the monsters can defeat more powerful enemies.